Hi everyone. I ve got a problem with my 740. Today in the morning there wasn't any problem but a few hours later when i start the engine it dies immediately. When i push the gas pedal it works but when i release it it dies. If u got any idea what could cause the problem please help me.

Yes its pretty tight. I changed the o rings but there is still air in the fuel. Do i have to bleed out the air? And how?

Did you just replace the O-rings, or did you change the whole filter? Did you check to make sure an old inner O-ring wasn't stuck on the filter head snout when the filter was off? Loss of seal on outer O-ring to seal is a prime source of air in fuel and an old, restricted filter makes things worse, puts more pressure on that seal. If there's an old O-ring (or two or three!) stuck up above, which is quite common, that will make it feel like the filter is screwed on tight but still prevent that outer O-ring from sealing -- or can make a weak seal that eventually backs off and starts leaking later on.

It sounds like you are sure there is air in the fuel. Does this mean that you are seeing visible air bubbles in the transparent fuel line between the filter and the IP when the engine is running? If so, you should be looking for air leaks at the filter or somewhere upstream from there -- most common cause is loose and/or clogged fuel filter but a bad hose or banjo connection at the filter head could also be a cause, or restricted tank pickup/leaking connections there, etc.

Based on what you've described so far, I still think your first step should be to start fresh with a brand new, high-quality filter, ensure there's no old O-ring stuck on the filter head, prefill the filter with new, clean fuel (or ATF, etc -- not fuel drained from your old filter!), and put it together and see what happens. If there are still signs of air ingress into the fuel from the filter to the IP after that, you'll need to work backwards from there and find the source. Remember that this motor does not recirculate fuel from the IP return back to the filter, it only returns to the tank, so that means if you're seeing air in the fuel while running the air leak is not from the IP but from something in the delivery system upstream from it.

On the other hand, if you're seeing good, air-free fuel flowing from filter to IP but still have symptoms of air in the system, that might point you to a leaky IP shaft seal or other air leak *downstream* of the filter. Depends what evidence you're basing your conclusion that there's air in the fuel on -- visual signs in the fuel line, or symptoms alone? Starting and quickly stalling is a fairly common symptom of loss of IP prime, e.g. from a leaking shaft seal or head seal or throttle shaft O-ring, but usually in those cases if you can get it reprimed and restarted it will continue running without struggle until it sits again. Yours sounds more like severe fuel inlet restriction or aeration.

Bleeding out the air is generally only helpful to get an engine running that won't start at all. If yours starts, it should be able to work out any other air quickly while running. And if it is still leaking air in ahead of the IP, then bleeding it out after the IP won't help much. I'd be focused on finding out how the air got in (or is getting in) rather than working to get it out.

Thanks a lot for te help! I think i solve that issue with the air in the fuel becausw there is no more bubbles in the hose but now it doesn't want to start and i think i have to change my glow plugs because they are very old. Can u tell me how to reach them because its really really hard, is there any hack or something.